Structures and methods for processing a semiconductor substrate

ABSTRACT

The present disclosure relates to exclusion rings for use in processing a semiconductor substrate in a processing chamber, such as a chemical vapor deposition chamber. The exclusion ring includes an alignment structure that cooperates with an alignment structure on a platen on which the exclusion ring will rest during processing of the wafer. The first alignment structure includes a guiding surface which promotes the reception of and positioning of the second alignment structure within the first alignment structure. Methods of utilizing the described exclusion rings are also described.

BACKGROUND

Chemical vapor deposition (“CVD”) is a gas reaction process commonlyused in the semiconductor industry to form thin layers of material,known as films, over an integrated circuit substrate. The CVD process isbased on the thermal, plasma, or thermal and plasma decomposition andreaction of selected gases. The most widely used CVD films are silicondioxide, silicon nitride, and polysilicon, although a wide variety ofCVD films suitable for insulators and dielectrics, semiconductors,conductors, superconductors, and magnetics are well known.

Particulate contamination of CVD films must be avoided. A particularlytroublesome source of particulates in the chemical vapor deposition ofmetals and other conductors is the film that forms on the edge andbackside of the wafer under certain conditions. For example, if thewafer edge and backside are unprotected or inadequately protected duringdeposition, a partial coating of the CVD material forms on the waferedge and backside, respectively. This partial coating tends to peel andflake easily for some types of materials, introducing particulates intothe chamber during deposition and subsequent handling steps.

In atomic layer deposition (ALD), a film is deposited layer by layer bysuccessive dosing and activation steps. ALD is used to generateconformal films on high aspect ratio structures. In some ALD processes,film deposition on the backside of the wafer is difficult to avoidbecause the film can be deposited through any gap accessing the waferbackside. Backside deposition is unwanted for a number of reasons, oneof which is that excess film on the backside of the wafer is susceptibleto flaking, e.g., during wafer transport. If flakes from the backside ofthe wafer come into contact with a wafer (either the same wafer or adifferent wafer), the wafer becomes contaminated and defects can result.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a cross-sectional view of a process chamber for carrying out aprocess on a substrate in accordance with embodiments of the presentdisclosure.

FIG. 2 is a bottom view of an exclusion ring in accordance with anembodiment of the present disclosure.

FIG. 3 is a schematic enlarged view of an exclusion ring on a platen inaccordance with an embodiment of the present disclosure.

FIG. 4 is a schematic enlarged view of a first alignment structure on anexclusion ring and a second alignment structure on a platen inaccordance with an embodiment of the present disclosure.

FIG. 5 is a cross-sectional view of a first alignment structure inaccordance with an embodiment of the present disclosure.

FIG. 6 is a schematic view of an exclusion ring being placed on a platenin accordance with an embodiment of the present disclosure.

FIG. 7 schematic view of the flow of a deposition control gas inaccordance with an embodiment of the present disclosure.

FIG. 8 is a schematic view of the flow of a deposition control gas.

FIGS. 9A and 9B are plan views of two first alignment structures on abottom surface of an exclusion ring in accordance with severalembodiments of the present disclosure.

FIGS. 10A and 10B are plan views of two second alignment structures onan upper surface of a platen in accordance with several embodiments ofthe present disclosure.

FIG. 11 is a cross-sectional view of a second alignment structure inaccordance with several embodiments of the present disclosure.

FIG. 12 is a flow chart of a method in accordance with an embodiment ofthe present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

A “substrate” as referred to herein, includes, but is not limited to,semiconductor wafers, semiconductor workpieces, and other workpiecessuch as optical planks, memory disks, and the like. Embodiments of theinvention may be applied to any generally flat workpiece on whichmaterial is deposited by the methods described herein and utilizing thedevices described herein.

“Vertical direction” and “horizontal direction” are to be understood asindicating relative directions. Thus, the horizontal direction is to beunderstood as substantially perpendicular to the vertical direction andvice versa. Nevertheless, it is within the scope of the presentdisclosure that the described embodiments and aspects may be rotated inits entirety such that the dimension referred to as the verticaldirection is oriented horizontally and, at the same time, the dimensionreferred to as the horizontal direction is oriented vertically.

One embodiment described herein is directed to an exclusion ring thatincludes a first alignment structure on its underside. This firstalignment structure cooperates with a second alignment structure on anupper surface of a platen upon which the exclusion ring will be placed.The cooperation between the first alignment structure and the secondalignment structure promotes proper alignment of the exclusion ring witha wafer supported by the platen. The first alignment structure includesguiding surfaces which increases the likelihood that the first alignmentstructure will receive and mate with the second alignment structure.Proper alignment and mating of the second alignment structure with thefirst alignment structure promotes alignment of the exclusion ring withthe wafer to within process tolerances.

Generally, excited species of processing gases may be generated toassist an atomic layer deposition (ALD) process as described herein.These species may be excited by plasma assistance, UV assistance (photoassistance), ion assistance (e.g., ions generated by an ion source), orcombinations thereof. The species are excited in, or in the vicinity of,the process region within the processing chamber housing to avoidrelaxation of the excited states before the ions reach the processregion of the batch processing chamber. An embodiment of the presentdisclosure is described in the context of a CVD process carried outwithout a plasma enhancement; however, the present disclosure is notlimited to an embodiment that carries out a CVD process without a plasmaenhancement. Embodiments of the present disclosure include othermaterial deposition processes that are carried out utilizing CVD withplasma enhancement.

In FIG. 1, wafer process stations 4 b, 4 c, and 4 d are visible in aside view of a high pressure CVD reaction chamber. Process stations 4b-4 d are not drawn to scale so that other features may be more readilyapparent. Process station 4 c, for example, includes a dispersion head12 c for introducing a process gas or gas mixture over a wafer to beprocessed; a platen 14 c for supporting the wafer to be processed; apedestal base 16 c, which includes a heater for heating platen 14 c andindirectly supplying heat to the wafer to be processed; and pin liftplatform 8 b, which is associated with pins 20 c, 21 c and 22 c (hidden)for lifting and lowering the wafer to be processed in coordination withactivation of a wafer transport mechanism 10. Similarly, process station4 b includes gas dispersion head 12 b, platen 14 b, pedestal base 16 b,and pin lift platform 8 a in association with pins 20 b, 21 b and 22 b.Similarly, process station 4 d includes gas dispersion head 12 d, platen14 d, pedestal base 16 d, and pin lift platform 8 b in association withpins 20 d, 21 d and 22 d (hidden). Also shown in FIG. 1 are a vacuumexhaust port 24, a spindle lift/rotation mechanism 26, and a pin liftmechanism 28. Process stations 4 a and 4 e are similar to processstations 4 b-4 d.

The exclusion guard lift assembly 420 is mounted within process chamber2 as shown in FIG. 1. The exclusion guard lift assembly 420 is coupledfor vertical movement with a rotatable wafer transport mechanism (notshown), while allowing the exclusion guard lift mechanism to berotationally static relative to the process stations 4 a-4 e duringrotation of the wafer transport mechanism.

The wafer to be processed is introduced into the process chamber 2 fromthe load lock chamber and is received at an empty load/unload stationand lowered onto raised lift pins of the empty load/unload station. Bycoordinating the rotation of wafer transport mechanism and the raisingand lowering of the lift pins, the wafers are transported to successiveones of the stations 4 b-4 d. As the wafer transport mechanism risestoward a level suitable for engaging wafers at the stations 4 b-4 d, theexclusion guard lift plate 422 also rises, thereby lifting exclusionguards to clear the space above the process stations 4 b-4 d fortransport of the wafers. As the wafer transport mechanism lowers fromthe level suitable for engaging wafers at the stations 4 b-4 d, theexclusion guard lift assembly 420 also lowers which consequently lowersthe lifted exclusion guards. Note that the motion of lift pins followsthe upward motion movement of transport mechanism and exclusion guardlift assembly 420, and precedes the downward movement of transportmechanism and exclusion guard lift assembly 420.

When the lift pins at the stations 4 b-4 d lower, the wafers to beprocessed are deposited on respective platens 14 b-14 d under respectivegas dispersion heads 12 b-12 d. Once the wafers are deposited on therespective platens 14 b-14 d, the wafers are preferably secured to therespective platens 14 b-14 d. Various techniques for securing the wafersto a wafer contact on a respective platen may be used. One preferabletechnique uses a vacuum chuck or electrostatic chuck.

When the exclusion guard lift assembly 420 is lowered, exclusion guardsare deposited on the top of the platens 14 b-14 d at the respectiveprocess stations 4 b-4 d, thereby exclusion guarding the wafers. Variousmeasures may be taken to retain the exclusion guards in place, forexample the exclusion guards may be made to be of a suitable weight sothat gravity acts to retain the exclusion guards in place. The exclusionguards may also be provided with a form of a keeper to help reversiblysecure the exclusion guard to other components of the respectivestations 4 b-4 d.

In order to stimulate the deposition of material onto the wafer beingprocessed, heat is provided to the wafer. One method of providing heatto the wafer involves heating each of the respective platens 14 b-14 dwhich transfers heat to the wafers sitting respectively thereon.

In some deposition operations, and particularly in the CVD deposition ofmetals and metal compounds such as tungsten, titanium nitride, andsilicides, one may wish to exclude deposition of material from the waferbackside and from the wafer edge. Excluding the deposition of materialon the wafer backside and/or the wafer edge involves introducing adeposition control gas near an edge of a wafer positioned on a platenfrom within each of the respective platens 14 b-14 d. The term“deposition control” gas means a gas that assists in controlling oreliminating chemical vapor deposition of material on certain portions ofthe wafer. For example, in one embodiment the deposition control gascontains chemicals, such as argon, that enhance deposition near areas ofa wafer such as the front side peripheral region of a wafer exposed to amixture of the deposition control gas and process gas, while excludingprocess gas from other portions such as the wafer backside and the waferedge to prevent unwanted deposition thereon. Since the edge of a wafermay have multiple planar and non-planar, beveled and non-beveled edgesurfaces, the term “edge” is intended to encompass all non-front side,non-backside surfaces. In accordance with embodiments of the presentdisclosure, the deposition gas is delivered to the platens 14 b-14 d andmade available for dispersion into the process chamber as describedbelow in more detail.

A variety of materials may be deposited using various process gases withsuitably selected deposition control gases. For example, to deposit atungsten film the product reactant WF₆ is used under the reactantconditions of H₂ and Ar. The WF₆ and H₂ gases are the reactantcomponents of the process. A suitable deposition control gas is argon,hydrogen, or a mixture of argon and hydrogen.

Uniformity of deposition near the front side periphery of the wafersbeing processed is further improved by including a reactive component ofthe process gas in the deposition control gas. In the example of thepreceding paragraph in which the reactant gases are WF₆ (productreactant) and H₂ and the carrier gas is Ar or Na or a mixture of Ar andN₂, improved uniformity of edge deposition is obtained by mixing thereactive component H₂ with Ar or Na or a mixture of Ar and N₂ to obtainthe deposition control gas. The proper proportion of reactive componentto inert gas is determined empirically. The process gas mixture (e.g.,WF₆+H₂+Ar flow ratios and WF₆+H₂+Ar total flow) and deposition controlgas mixture (e.g., H₂+Ar flow ratios and H₂+Ar total flow) areinteractively combined and changed to produce the best front side waferuniformity while maintaining process gas exclusion from the wafer edgeand backside.

In depositing other films, other process gases with different reactantcomponents may be used. Suitable inert gases for use in the depositioncontrol gas mixture include argon, nitrogen, and helium or any suitablecombination thereof. An inert gas is any gas that does not reactadversely with the materials present in the process chamber and in thegas distribution system, and that does not participate in the chemicalreactions involved. Moreover, it is desirable that the thermalconductivity and heat capacity of the inert gas be sufficient to achievegood temperature uniformity across the wafers being processed.Embodiments of the present disclosure are not limited to the gasesdescribed above. Embodiments in accordance with the present disclosureutilize other reactant gases and carrier gases.

Exclusion of process gas from the wafer backside and edge is assisted bythe use of a structure such as the “exclusion guard” or minimum overlapexclusion ring (“MOER”) in combination with the use of the depositioncontrol gas during processing. A generalized embodiment of an exclusionguard, which is made of any suitable material such as metal or ceramic(including, for example, alumina), is exclusion guard 1000 shown in FIG.2. Exclusion guard 1000 includes an annular body 200. The annular body200 includes an outer peripheral edge 201, an inner peripheral edge 203,an upper surface 207 and a lower surface 209. An open or void centralregion 205 is located radially inward from the inner peripheral edge203. A flange 404 in FIG. 3 extends from the lower surface 209 adjacentto the outer peripheral edge 201. The exclusion guard of FIG. 2 includesan alignment hole 1004 on the underside of flange 404 and an alignmentslot 1006 on the underside of flange 404. In other embodiments theexclusion guard includes one or the other of an alignment hole 1004 andan alignment slot 1006. In other embodiments, the exclusion guard orring includes more than one alignment hole 1004 or more than onealignment slot 1006. Further details of the alignment hole 1004 andalignment slot 1006 are provided below.

FIG. 3 illustrates an exploded partial cross sectional view of anexclusion guard 800 residing on platen 202. The exclusion guard includesa peripheral downward extending flange 404. During processing,deposition control gas is introduced into platens 14 b-14 d fordispersion into the process chamber as discussed above. Restrictiveopening 706 serves to equalize the pressure in a plenum formed in partby gas groove 210 and the cavity between gas groove 210 and extension804. As a result deposition control gas flow, as indicated by the arrowson FIG. 3 is uniform through the restrictive opening 706 over the entirewafer front side periphery. This uniform deposition control gas flowdenies or reduces process gas access to the edge and backside of thewafer 402, thereby preventing or reducing material deposition on thesesurfaces.

To improve the extent of uniform material deposition on the wafer 402front side periphery, the deposition control gas preferably includes oneor more reactive components of the process gas as discussed above. Thereactive component in the deposition control gas enhances deposition atthe wafer 402 periphery to compensate for any process gas flowinterference in a region caused by the deposition control gas ventingfrom restrictive opening 706 and the physical presence of a portion ofthe extension 804 extending over the wafer 402 into the flow pattern ofthe process gas. For example, when depositing W and using H₂ as thereactive component in the deposition control gas, the deposition rate ofW (produced by reacting WF₆ with H₂) varies proportionately with thesquare root of the H₂ concentration, i.e., a four times increase in thequantity of H₂ increases the deposition rate of W by a factor of two.Therefore, to enhance the deposition of W by a factor of two at thefront side periphery of a wafer, the H₂ concentration is increased by afactor of four at the front side periphery of the wafer. Note that agreater overall concentration of H₂ may be required in the depositioncontrol gas to assure that an increase of four times reaches the waferfront side periphery. Note also that when increasing a reactivecomponent in the deposition control gas, for example H₂, a reactivecomponent in the process gas, for example WF₆, is preferably supplied tosustain the kinetically possible deposition rate. Otherwise, thereaction may be “starved” in regions rich in H₂ and deficient in WF₆.

The flow rate of the deposition control gas is inversely related to thequantity of reactive component present in the deposition control gas.Therefore, when the flow rate is reduced, the quantity of a reactivecomponent (e.g., H₂) may be increased to achieve the desired uniformityof deposition on the frontside of wafer 402, and vice versa.

In some processes a reduced flow of deposition control gas may notdeliver sufficient reactive component(s) to the interference region toovercome perturbation of the process gas flow by the exclusion guard 800and the dilution effect of the deposition control gas venting from therestrictive opening 706, so that the extent of uniform deposition maynot be as great as desired. Providing orifices in an exclusion guardminimizes deposition control gas interference while preferablyincreasing the supply of reactive components to the wafer 402 front sideperiphery. For example, the exclusion guard 1000 of FIG. 2 includes aplurality of orifices 1002. These holes are illustrated in FIG. 3 andidentified by reference number 902. Holes 902 extend from the topsurface of exclusion guard 800 to a deposition control gas source. Thetotal amount of deposition control gas entering the process chamberequals the amount of deposition control gas flowing through restrictiveopening 706 and holes 902. Therefore, the total amount of depositioncontrol gas can be increased in the region of the process chamber overthe wafer front side periphery without increasing the flow rate ofdeposition control gas through restrictive opening 706. The holes 902should preferably vent a portion of the deposition control gas into theprocess chamber toward the outside edge of exclusion guard 800 to createa venturi effect to draw the process gas along the wafer front sidetoward the leading edge of the extension 804 during wafer processing,even while some of the deposition control gas diffuses back toward theleading edge of the extension 804 to increase the supply of reactant gascomponents to the front side periphery of wafer 402, thereby improvinguniform wafer front side deposition.

Referring back to FIG. 2, a bottom view of an exclusion guard orexclusion ring 1000 having an array of orifices through which depositioncontrol gas flows to promote a uniform deposition nearly out to the edgeof the wafer being processed. The orifices or holes 920 are shown assolid circles. In the illustrated embodiment, there are 180 holes 920spaced apart equally with the holes each having an equal diameter.Because of the extremely small width of the restrictive opening betweenthe extension 804 and the front side of the mounted wafer, a largepercentage of the deposition control gas vents through the holes 920. Analignment hole 1004 and alignment slot 1006 are also shown on theunderside of the exclusion ring 1000. Alignment hole 1004 and alignmentslot 1006 are located in flange 404. The outside edge of exclusion guard1000 has indentations 1008 and 1010 to accommodate adjacent exclusionguards in process chamber 2 of FIG. 1.

As described above with reference to FIG. 3, exclusion ring 800 residingon platen 202 includes an extension 804 that overlaps a peripheralportion of the upper surface or front side of wafer 402. The exclusionring 800 also overlaps the peripheral edge 203 of wafer 402. Exclusionring 800 also defines one boundary of the restrictive opening 706. Theother boundary of the restrictive opening 706 is defined by the uppersurface of wafer 402. Properly locating and aligning the exclusion ring800 relative to the wafer 402 ensures that the desired portions of theperipheral portion of the upper surface of wafer 402 and peripheral edgeof wafer 402 is overlapped by the exclusion ring 800. Such properlocation of the exclusion ring 800 promotes flow of the depositioncontrol gas through restrictive opening 706 and uniform flow over theentire wafer upper surface periphery. This uniform flow of depositioncontrol gas promotes formation of deposited films on the central regionsof the wafer 402 and near the periphery of wafer 402 that are uniformand within with product specifications. When the exclusion ring is notproperly located and aligned with the wafer 402, portions of the uppersurface of wafer 402 can be left uncovered or covered to a lesser degreethan desired and other portions of the upper surface of wafer 402 can becovered to a greater degree than desired. Both of these situations canresult in deposited materials that do not exhibit uniform properties,e.g., thickness.

Referring to FIGS. 4 and 5, an embodiment of an alignment structure 213,e.g., alignment slot 1006 in FIG. 2, has a shape of an isoscelestrapezoid formed within the underside of exclusion ring 1000, and morespecifically, in the underside of flange 404. The isosceles trapezoidshape of alignment structure 213 is characterized by a line of symmetrybisecting one pair of opposite sides. In FIGS. 4 and 5, the oppositesides are a top side 408 and a bottom side 410. Alignment structure 213is further characterized by a diagonal surface forming a guiding surface406 a and diagonal surface forming a guiding surface 406 b that areequal in length and each form an equal angle with bottom side 410 andequal angle with top side 408.

In FIG. 4, a second alignment structure 400 includes an alignment pinthat is present on an upper surface 211 of platen 202. In theillustrated embodiment of the second alignment structure 400 in FIG. 4,a lower portion of the alignment pin is embedded in an upper surface 211of platen 202. An upper portion of the second alignment structureextends above the upper surface 211 of platen 202 by a distance H1. Inthe embodiment of FIG. 4, the upper portion of the second alignmentstructure that extends above the upper surface 211 of platen 202 has around shape, e.g., is ball shaped. This ball-shaped upper portion has adiameter of W3. In other embodiments in accordance with the presentdisclosure, the upper portion of the second alignment structure 400 isnot round shaped. For example, the upper portion of the second alignmentstructure 400 can have a square or rectangular cube shape, e.g., theshape of an isosceles trapezoid. In some embodiments, the shape of theupper portion of the second alignment structure 400 is substantiallycongruent with the shape of the first alignment structure 213. In otherembodiments, the second alignment structure 400 is comprised of only theupper portion that extends above the upper surface of platen 202 anddoes not include the lower portion that is contained within the body ofplaten 202. When the second alignment structure includes only the upperportion that extends above the upper surface of platen 202, the upperportion is secured to the upper surface 211 of platen 202. In accordancewith embodiments described herein, when second alignment structure 400is properly seated within first alignment structure 213, exclusion ring800 located in a desirable position and is aligned with wafer 402 suchthat deposition control gas flow from the restrictive opening 706between wafer 402 and exclusion ring 800 is uniform and flows over theentire wafer front side periphery. Such uniform flow of the depositioncontrol gas promotes uniform material deposition near the wafer frontside periphery and reduces or prevents non-uniform wafer deposition nearthe wafer front side periphery.

FIG. 5 shows a cross section of first alignment structure 213 and aportion of flange 404 in which first alignment structure 213 is located.The cross section in FIG. 5 is taken along line 5-5 in FIG. 2. The crosssection of alignment structure 213 along line 5A-5A in FIG. 2 isidentical to the cross section of first alignment structure 213 alongline 5-5 in FIG. 2.

Referring to FIG. 5 first alignment structure 213 includes a topside 408having a length W1. Opposite to top side 408, first alignment structure213 includes bottom side 410 having a length W2. Bottom side 410 isparallel to top side 408. In some embodiments, topside 408 is parallelto upper surface 207 of annular body 200 of exclusion ring 800. In theillustrated embodiment, W2 is greater than W1. The distance betweentopside 408 and bottom side 410 is height H. First alignment structure213 also includes guiding surfaces 406 a and 406 b formed by opposinglegs or diagonal sides of the isosceles trapezoid shape of alignmentstructure 213. In the illustrated embodiment, these diagonal sides eachhave a length L. Embodiments of the present disclosure are not limitedto diagonal sides that are of equal length. For example, in otherembodiments, the length of one diagonal side forming guiding surface 406a is less than or greater than the length of the diagonal side formingguiding surface 406 b. In embodiments where the length of one diagonalside is unequal to the length of the other diagonal side, the parallelrelationship of topside 408 and bottom side 410 can be maintained byadjusting the slant or slope of either diagonal side forming guidingsurfaces 406 a or 406 b.

The first alignment structure 213 is further characterized by an angletheta (θ), formed between bottom side 410 and the diagonal side formingguiding surface 406 a, that has an arc sine equal to H/L. When bottomside 410 is parallel to lower surface 209 of annular body 200, thediagonal side forming guiding surface 406 a slopes at an angle θrelative to the lower surface 209 of annular body 200. When the diagonalside forming guiding surface 406 a and the diagonal side forming guidingsurface 406 b are equal in length, the diagonal side forming guidingsurface 406 b also forms an angle θ with bottom side 410 and has an arcsine equal to H/L. When bottom side 410 is parallel to lower surface 209of annular body 200, the diagonal side forming guiding surface 406 bslopes at an angle θ relative to the lower surface 209 of annular body200. The diagonal side forming guiding surface 406 a forms an angle psi(ϕ) with the top side 408 of first alignment structure 213. Angle ischaracterized by an arc cosine that is equal to H/L. Similarly, thediagonal side forming guiding surface 406 b forms and an angle psi (ϕ)with the top side 408 of first alignment structure 213 that has an arccosine equal to H/L. When the top side 408 is parallel to upper surface207 of annular body 200 of exclusion ring 800, the diagonal side formingguiding surface 406 a slopes at an angle ϕ relative to upper surface207. When the top side 408 is parallel to upper surface 207 of annularbody 200 of exclusion ring 800, the diagonal side forming guidingsurface 406 b slopes at an angle ϕ relative to upper surface 207.

In some embodiments, the angle is greater than 90°. For example, theangle ϕ is greater than 100°, greater than 110°, greater than 120°,greater than 130° or greater than 140°. In some embodiments, the sum ofangle θ and angle is 180°. In some embodiments angle θ is less than 90°.For example, in some embodiments the angle θ is less than 80°, is lessthan 70°, is less than 60° or is less than 50°.

In accordance embodiments of the present disclosure, W2 is greater thanW1. For example, the ratio of W2 to W1 is between about 1.1 to about2.0. In other embodiments, the ratio of W2 to W1 is between about 1.25to about 1.75. In other embodiments, the ratio of W2 to W1 is betweenabout 1.5 to about 1.65.

In accordance with embodiments of the present disclosure, the ratio ofW1 to H is between 0.5 to 2.0. In accordance with other embodiments, theratio of W1 to H is between about 1.0 and 1.5. In accordance with otherembodiments, the ratio of W1 to H is between about 1.1 and 1.4. Inaccordance with other embodiments, the ratio of W1 to H is between about1.2 and 1.3.

In accordance with embodiments of the present disclosure, the ratio ofW2 to H is between about 1 to about 3. In accordance with otherembodiments, the ratio of W2 to H is between about 1.5 and 2.5.

In accordance with embodiments of the present disclosure, the diameteror width W3 of the upper portion of second alignment structure 400 is atleast 80% of the dimension W1. In other embodiments, W3 is at least 85%of the dimension W1. In other embodiments, W3 is at least 90% of thedimension W1. In other embodiments, W3 is at least 95% of the dimensionof W1. A second alignment structure 400 having a dimension W3 within theranges described above fits within the first alignment structure 213with tolerances that result in the exclusion ring 800 being aligned withthe wafer within process tolerances. The foregoing dimensions and ratiosof dimensions for the first alignment structure 213 are selected tooptimize the likelihood that the second alignment structure 400 will bereceived by the second alignment structure 400 and that the secondalignment structure 400 will become properly seated within the firstalignment structure 213 and therefore properly aligned over the wafersurface.

In accordance with embodiments of the present disclosure, the upperportion of the second alignment structure 400 extends above the uppersurface 209 of platen 202 by a distance H₁. In some embodiments, H₁ isat least 80% of the dimension H. In other embodiments, H₁ is at least85% of the dimension H. In other embodiments, H₁ is at least 90% ofdimension H. In other embodiments, H₁ is at least 95% of dimension H.

Referring to FIGS. 9A and 9B, bottom views of two embodiments of a firstalignment structure 213 in flange 404 are provided. FIG. 9A is a view ofa first alignment structure 213 in the form of an alignment slot 1006formed in the underside of flange 404 of exclusion ring 1000 in FIG. 2.The embodiment of a first alignment structure 213 in FIG. 9A is arectangular shaped depression (e.g., square shaped depression) having atleast two guiding surfaces 406 a and 406 b extending between topside 408and bottom side 410 of first alignment structure 213. FIG. 9B is a viewof an alternative first alignment structure 213 in the form of analignment hole 1004. Alignment hole 1004 differs from alignment slot1006 by being circular in shape when viewed from below. First alignmentstructure 213 in the form of alignment hole 1004 includes a guidingsurface 406 that extends between topside 408 and bottom side 410. Across section of alignment hole 1004 along line 5B-5B in FIG. 2 willhave the same shape as the cross section of alignment slot 1006illustrated in FIG. 5. The cross section of alignment hole 1004 alongline 5C-5C in FIG. 2 will have the same cross section shape as the crosssection taken along line 5B-5B in FIG. 2. In accordance with the presentdisclosure, first alignment structure 213 can have other shapes,provided such other shapes include the guiding surfaces of the firstalignment structure 213 and mate with the second alignment structure 400to position an exclusion ring so that it is aligned over wafer 402.

Referring to FIGS. 10A and 10B, top views of two embodiments of a secondalignment structure 400 on upper surface 211 of platen 202 are provided.FIG. 10A is a view of a second alignment structure 400 for mating withthe alignment slot 1006 on the underside of flange 404 of exclusion ring1000 in FIG. 2. This embodiment of a second alignment structure 400 inFIG. 10A is a rectangular shaped protrusion (e.g., square shapedprotrusion) having at least two sloped surfaces 606 a and 606 bextending between top 608 and bottom 610 of second alignment structure400. FIG. 9B is a view of an alternative second alignment structure 400for mating with an alignment hole 1004. The second alignment structure400 of FIG. 10B differs from the second alignment structure 400 of FIG.10A by being circular in shape when viewed from above. The secondalignment structure of FIG. 10A is similar to the second alignmentstructure of FIG. 4. Second alignment structure 400 in FIG. 10B includesa sloped surface 606 that extends between top 608 and bottom 610. Across section of alignment structure 400 of FIGS. 10A and 10B isillustrated in FIG. 11. The second alignment structures 400 of FIGS. 10Aand 10B can have a cross-sectional shape that is congruent with orsubstantially congruent with the cross-sectional shape of the firstalignment structure 213 in FIG. 5. In FIG. 11 the dimensions of thesecond alignment structure 400 that are congruent with or aresubstantially congruent with the dimensions of the first alignmentstructure 213 are identified with the same alphabetical label and with aprime symbol added, i.e., L′, H′, W1′, W2′. Second alignment structure400 includes a topside 608, an opposing bottom side 610 which aresubstantially parallel to each other. Extending between topside 608 andbottom side 610 is at least one slanted or angled surface 606. Theslanted or angled surface(s) 606 form angle θ′ and angle ϕ′. Thedescriptions above regarding dimensions L, H, W1 and W2 with regard tothe FIG. 5 and first alignment structure 213 and the angles θ and ϕ areequally applicable to dimensions L′, H′, W1′, and W2′ and to angles θ′and ϕ′ and are not reproduced here in the interest of brevity.

Referring to FIGS. 4 and 7, an exclusion ring 800 formed in accordancewith embodiments of the present disclosure is utilized to promotealignment of the exclusion ring 800 with a wafer 402, the peripheraledges of which the exclusion ring is designed to cooperate with in orderto ensure formation of films of material near the peripheral edges ofthe wafer that have uniform properties, e.g., thickness. FIG. 4illustrates a side view of exclusion ring 800 properly seated on anupper surface 211 of platen 202. In FIG. 4, second alignment structure400 is nested in first alignment structure 213. In the embodimentillustrated in FIG. 4, the width of first alignment structure 213 isgreater than the width of the upper portion of second alignmentstructure 400 that extends into first alignment structure 213. Thedifference in the width between the upper portion of the secondalignment structure and the width of the first alignment structure 213is such that while exclusion ring 800 may shift from left to right inFIG. 4 and change the alignment of the exclusion ring 800 with wafer402, the amount of such shifting is not so great that the alignment ofthe exclusion ring 800 with wafer 402 falls outside process tolerances.When exclusion ring 800 is properly seated on platen 202 and alignedwith wafer 402, a portion of deposition control gases 250 from theplaten flow through the orifices 902 in exclusion ring 800 as shown inFIG. 7. Another portion of the deposition control gases 250 flow betweenextension 804 and wafer 402 and across the upper surface of wafer 402.These flows of deposition control gases promotes formation of uniformfilms on the upper surface of wafer 402.

FIG. 6 illustrates an embodiment illustrating how the first alignmentstructure 213 in accordance with embodiments of the present disclosurepromote the proper alignment of exclusion ring 800 with wafer 402. InFIG. 6, exclusion ring 800 is placed in a position over platen 202 andis moving in the left hand direction as indicated by arrows 440. Asillustrated, an upper portion of second alignment structure 400 formedin upper surface 211 of platen 202 contacts a lower surface 209 ofexclusion ring 800. As the movement of exclusion ring 800 in thedirection of arrow 440 continues, the upper portion of second alignmentstructure 400 begins to contact guide surface 406. Upper portion ofsecond alignment structure 400 then cooperates with and slides alongguide surface 406 until the second alignment structure 400 is centeredwithin first alignment structure 213. Proper alignment of the upperportion of second alignment structure 400 within first alignmentstructure 406 is illustrated in FIG. 4. In FIG. 4, the upper portion ofsecond alignment structure 400 is centered within the first alignmentstructure 213. If second alignment structure 400 were to be placed inthe position illustrated in FIG. 6 with second alignment seat 400 notproperly seated within first alignment structure 213 proper flow ofdeposition control gases is impeded. For example, referring to FIG. 8,if exclusion ring 800 is left in the position illustrated in FIG. 6, alarger portion of deposition control gases 250 will flow betweenextension 804 and the upper surface of wafer 402 as indicated by arrow805 and less deposition control gases will flow through orifice 902.This alteration in the amount of deposition control gases directed tothe two different flow pass can adversely affect the uniformity of filmsdeposited during the vapor deposition process.

It should be appreciated that the greater degree the shape of theportion of the second alignment structure 400 that extends above theupper surface 211 of platen 202 is congruent with the shape of the firstalignment structure 213, the less the exclusion ring 800 can shift andchange the alignment with the wafer once the first alignment structure213 and second alignment structure 400 are mated or nested together.

In accordance with other embodiments of the present disclosure, thelocation of the first alignment structure and the second alignmentstructure can be reversed. In other words, the first alignment structurecan be formed on the platen and the second alignment structure can beformed on the exclusion ring. In one specific example of such anembodiment, the guide pin or protruding alignment structure is formed onthe underside of the exclusion ring and the alignment slot or alignmenthole or alignment depression for receiving the protruding alignmentstructure is formed on the upper surface of the platen.

FIG. 12 is a method for positioning an exclusion ring on a platen of achemical vapor deposition tool according to one embodiment. At 1210, themethod 1200 includes positioning an exclusion ring over a platen of achemical vapor deposition tool. One example of an exclusion ring is theexclusion ring 1000 illustrated in FIG. 2 or the exclusion ring 800 inFIG. 3. At 1215, the method includes contacting a first alignmentstructure of the exclusion ring with a second alignment structure of theplaten. At 1220, method 1200 includes maintaining contact between aguiding surface of a first alignment structure and a second alignmentstructure, the guiding surface slope being an angle greater than 90°relative to an upper surface of the exclusion ring. One example of afirst alignment structure is the first alignment structure 213illustrated and described in FIGS. 4 and 5. One example of a secondalignment structure is the second alignment structure 400 illustratedand described in FIGS. 4, 10A, 10B and 11. At 1230, the method 1200includes, while maintaining contact between the guiding surface of thefirst alignment structure and the second alignment structure, moving thefirst alignment structure relative to the second alignment structure. At1240, method 1200 includes aligning the first alignment structure withthe second alignment structure.

In one embodiment of the present disclosure, an exclusion ring for achemical deposition tool is provided. The exclusion ring includes anannular body, an outer peripheral edge, an inner peripheral edge, anupper surface and a lower surface. An open region is radially inwardfrom the inner peripheral edge of the annular body. A flange extendsfrom the lower surface of the annular body adjacent the outer peripheraledge of the annular body. The exclusion ring includes a first alignmentstructure on the flange, the first alignment structure including aguiding surface. The guiding surface slopes at an angle greater than 90°relative to the upper surface of the annular body.

In one embodiment, a chemical vapor deposition system is provided. Thechemical vapor deposition system includes an exclusion ring thatincludes an annular body. The annular body of the exclusion ringincludes an outer peripheral edge, an inner peripheral edge, an uppersurface and a lower surface. An open central region extends radiallyinward from the inner peripheral edge of the annular body. A flangeextends from the lower surface of the annular body adjacent the outerperipheral edge of the annular body. A first alignment structure isprovided on the flange. The first alignment structure includes a guidingsurface. The guiding surface slopes at an angle less than 90° relativeto the lower surface of the annular body. The chemical vapor depositionsystem includes a platen including an upper surface and a lower surface.A second alignment structure is provided on the upper surface of theplaten.

In one embodiment, a method of positioning an exclusion ring on a platenof a chemical vapor deposition tool is provided. The method includespositioning the exclusion ring over the platen. The exclusion ringincludes an annular body including an outer peripheral edge, an uppersurface and a lower surface. A flange extends from the lower surface ofthe annular body adjacent the outer peripheral edge of the annular body.The first alignment structure is on the flange. The first alignmentstructure includes a guiding surface which slopes at an angle greaterthan 90° relative to the upper surface of the annular body. The platenincludes an upper surface and a second alignment structure on the uppersurface of the platen. The method includes contacting the firstalignment structure with the second alignment structure. Contact betweenthe first alignment structure and the second alignment structure ismaintained. While maintaining such contact between the first alignmentstructure and the second alignment structure, the first alignmentstructure is moved relative to the second alignment structure. The firstalignment structure in the second alignment structure are moved relativeto each other until the first alignment structure and the secondalignment structure are aligned.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. An exclusion ring for a chemical vapor deposition tool, the exclusionring comprising: an annular body, the annular body including an outerperipheral edge, an inner peripheral edge, an upper surface and a lowersurface; an open central region radially inward from the innerperipheral edge; a flange extending from the lower surface adjacent tothe outer peripheral edge; and a first alignment structure on theflange, the first alignment structure including a guiding surface, theguiding surface sloping at an angle greater than 90 degrees relative tothe upper surface of the annular body.
 2. The exclusion ring of claim 1,wherein the first alignment structure has a cross section in a planeparallel to a plane of the upper surface, the cross section of the firstalignment structure being round.
 3. The exclusion ring of claim 1,wherein the first alignment structure has a cross section in a planeparallel to a plane of the upper surface, the cross section of the firstalignment structure being rectangular.
 4. The exclusion ring of claim 3,wherein the cross section of the first alignment structure is square. 5.The exclusion ring of claim 1, wherein the guiding surface slopes at anangle greater than 110° relative to the upper surface of the annularbody.
 6. The exclusion ring of claim 1, wherein the first alignmentstructure has a dimension H and the guiding surface has a length L, theguiding surface and the lower surface defining an angle θ having an arcsine equal to H/L.
 7. The exclusion ring of claim 6, wherein the firstalignment structure has a dimension W1, the ratio of W1 to H rangingbetween 0.5 to 2.0.
 8. A chemical vapor deposition system, comprising:an exclusion ring including an annular body, the annular body includingan outer peripheral edge, an inner peripheral edge, an upper surface anda lower surface; an open central region radially inward from the innerperipheral edge; a flange extending from the lower surface adjacent theouter peripheral edge; a first alignment structure on the flange, thefirst alignment structure including a guiding surface, the guidingsurface sloping at an angle less than 90 degrees relative to the lowersurface of the annular body; a platen, the platen including an uppersurface and a lower surface; and a second alignment structure, thesecond alignment structure on the upper surface of the platen.
 9. Thechemical vapor deposition system of claim 8, wherein the first alignmentstructure has a cross section in a plane parallel to a plane of theupper surface, the cross section of the first alignment structure beingrectangular.
 10. The chemical vapor deposition system of claim 9,wherein the second alignment structure has a cross section in a planeparallel to a planne of the upper surface, the cross section of thesecond alignment structure being rectangular.
 11. The chemical vapordeposition system of claim 8, wherein the guiding surface slopes at anangle less than 80° relative to the lower surface of the annular body.12. The chemical vapor deposition system of claim 8, wherein the firstalignment structure has a dimension H and the guiding surface has alength L, the guiding surface and the lower surface defining an angle θhaving an arc sine equal to H/L.
 13. The chemical vapor depositionsystem of claim 8, wherein the first alignment structure has a dimensionW1 and the second alignment structure has a dimension W3, W3 being atleast 80% of W1.
 14. The chemical vapor deposition system of claim 13,wherein the first alignment structure has a dimension W1 and the secondalignment structure has a dimension W3, W3 being at least 95% of W1. 15.The chemical vapor deposition system of claim 8, wherein the secondalignment structure extends above the upper surface of the platen adistance equal to a dimension H of the first alignment structure. 16.The chemical vapor deposition system of claim 8, wherein the firstalignment structure extends from a lower surface of the exclusion ringand the second alignment structure extends into the upper surface of theplaten.
 17. A method of positioning an exclusion ring on a platen of achemical vapor deposition tool, the method comprising: positioning theexclusion ring over the platen, the exclusion ring including: an annularbody including an outer peripheral edge, an upper surface and a lowersurface, a flange extending from the lower surface adjacent the outerperipheral edge and a first alignment structure on the flange, the firstalignment structure including a guiding surface, the guiding surfacesloping at an angle greater than 90 degrees relative to the uppersurface of the annular body, and the platen including an upper surfaceand a second alignment structure, the second alignment structure on theupper surface of the platen; contacting the first alignment structurewith the second alignment structure; maintaining contact between thefirst alignment structure and the second alignment structure; whilemaintaining contact between the first alignment structure and the secondalignment structure, moving the first alignment structure relative tothe second alignment structure; and aligning the first alignmentstructure with the second alignment structure.
 18. The method of claim17, wherein aligning the first alignment structure with the secondalignment structure includes seating the second alignment structurewithin the first alignment structure.
 19. The method of claim 17,wherein aligning the first alignment structure with the second alignmentstructure includes seating the first alignment structure within thesecond alignment structure.
 20. The method of claim 17, wherein movingthe first alignment structure relative to the second alignment structureincludes sliding the second alignment structure along a guiding surfaceof the first alignment structure.